Interfacial Ion Fluxes at Nanostructured Thin Films

2002 ◽  
Vol 752 ◽  
Author(s):  
Nancy N. Kariuki ◽  
Jin Luo ◽  
Li Han ◽  
Mathew M. Maye ◽  
Melissa J. Patterson ◽  
...  
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Copper Ions ◽  
Three Dimensional ◽  
Volume Ratio ◽  
Reduction Process ◽  
Ion Fluxes ◽  
Gold Nanocrystals ◽  
Film Electrolyte ◽  
Infrared Reflection Spectroscopy

ABSTRACTThin films derived from nanocrystal cores and functionalized linkers provide large surface-to-volume ratio and three-dimensional ligand framework. This paper describes the results of an investigation of the interfacial ion fluxes associated with redox reactivity and structural properties of such films using cyclic voltammetry, electrochemical quartz-crystal nanobalance, surface infrared reflection spectroscopy, and X-ray photoelectron spectroscopy. Films from gold nanocrystals of 2 nm core sizes and 11-mercaptoundecanoic acid were studied as a model system. First, the film coated on electrode surface displays redox-like voltammetric waves characteristic of the deprotonation-reprotonation of the carboxylic acid groups in the nanostructured network. This process is accompanied by mass changes. Secondly, the film exhibits capability for the complexation of copper ions via the nanostructured carboxylate framework. This process is also accompanied by interfacial fluxes of electrolyte cations across the electrode | film | electrolyte interface which compensate electrostatically the fixed negative charges in the reduction process.

A STUDY ON THE ELECTRODEPOSITION MECHANISM OF COBALT-NICKEL/COPPER MULTILAYER FROM SULFATE SOLUTION

2008 ◽  
Vol 22 (18n19) ◽  
pp. 3046-3059 ◽  
Author(s):  
S. S. MAHSHID ◽  
A. DOLATI
Keyword(s):  
Photoelectron Spectroscopy ◽  
Copper Ions ◽  
Three Dimensional ◽  
Compositional Analysis ◽  
Sulfate Solution ◽  
Nucleation Mechanism ◽  
Potential Range ◽  
Cyclic Voltammograms ◽  
Cobalt Nickel ◽  
Nickel Copper

The cobalt-nickel/copper multilayer films were prepared by electrodeposition process in sulfate solution using a three electrode cell. Cyclic voltammetry and double chronoampermetry techniques were utilized to characterize the multilayer system and to obtain the nucleation and growth mechanism. The cyclic voltammograms determined the reduction potential range of the three components and also clearly emphasized that electrodeposition of cobalt-nickel alloy was controlled by a kinetic process, while copper ions were reduced with diffusion-controlled mechanism. These results were confirmed with those which were extracted from the chronoampermetry curves. In addition, the current transients revealed that nucleation mechanism was a typical three-dimensional nucleation process. The Atomic Force Microscope images (AFM) of these multilayers also confirmed the three-dimensional nucleation mechanism. The compositional analysis of these multilayers was carried out by Atomic Absorption Spectroscopy (AAS) and X-ray Photoelectron Spectroscopy (XPS) methods. The bulk and surface compositional analysis both revealed that the amount of Copper component within the cobalt-nickel layers is less than 3%.

ELECTRONIC STRUCTURE OF Ag THIN FILMS ON A Ge(001) SURFACE

2002 ◽  
Vol 09 (02) ◽  
pp. 681-686 ◽  
Author(s):  
K. NAKATSUJI ◽  
M. YAMADA ◽  
S. OHNO ◽  
Y. NAITOH ◽  
T. IIMORI ◽  
...  
Keyword(s):  
Thin Films ◽  
Electronic Structure ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Recent Observation ◽  
Three Dimensional ◽  
Surface States ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Bulk Band

We have studied the electronic structure of Ag thin films of monoatomic height grown on a Ge(001) surface at 95 K by using photoelectron spectroscopy. All the surface states on the clean Ge surface vanished and Ag 5s derived state appeared in the bulk band gap just below the Fermi level. These suggest a strong interaction with the substrate. On the other hand, on three-dimensional (3D) islands formed on a room temperature substrate, small changes were found in Ge 3d spectrum from the clean surface. Each of the Ag 3D islands already had bulklike feature in the valence band structure. The results are consistent with recent observation by scanning tunneling microscopy.

Sol-Gel Synthesis of Highly Dispersed Cobalt Nanoparticles on Silica Thin Films

2005 ◽  
Vol 20 (11) ◽  
pp. 3094-3101 ◽  
Author(s):  
S.M. Park ◽  
W. Ki ◽  
J. Yu ◽  
H. Du
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Lower Layer ◽  
Layer Structure ◽  
Sol Gel ◽  
Reduction Process ◽  
Heat Treating ◽  
Cobalt Nanoparticles ◽  
Si Substrates ◽  
Silica Thin Films

Cobalt nanoparticles were synthesized on silica thin films by heat treating Co/silica films spun on thermally oxidized Si substrates. The as-deposited films were calcined in vacuum (∼0.03 Torr) for 2 h at 500 °C, followed by reduction in hydrogen at 650 °C for up to 15 h. The reduction process is characterized as one of time-dependent evolution of nanoparticles in both physical appearance and phase nature, eventually leading to the formation of well-dispersed Co nanoparticles, as ascertained by x-ray photoelectron spectroscopy and scanning electron microscopy. Slow conversion of Co ions into metallic Co observed in this study is ascribed to the absence of a Co3O4 phase that forms predominantly during calcination in air. Atomic force microscopy revealed a marked increase in the surface roughness of the film due to the development of nanoparticles. A distinct duplex-layer structure was observed in the reduced film, which consisted of the upper layer laden with nanoparticles and the lower layer essentially particle-free. The growth of the upper layer appears to be controlled by the upward diffusion of Co2+ in the film during the reduction process.

scholarly journals Removal of Copper Ions in Wastewater by Adsorption onto a Green Adsorbent from Winemaking Wastes

2019 ◽  
Author(s):  
Lorena Alcaraz ◽  
Irene García-Díaz ◽  
Francisco J. Alguacil ◽  
Félix A. López
Keyword(s):  
Activated Carbon ◽  
Photoelectron Spectroscopy ◽  
Moving Boundary ◽  
Copper Ions ◽  
Reduction Process ◽  
Sorption Process ◽  
Copper Adsorption ◽  
Green Adsorbent ◽  
Pseudo Second Order ◽  
Full Factorial

This article presents the copper ions adsorption process using an activated carbon from winemaking wastes. The pH, temperature, activated carbon amount and initial copper concentration were varied based on a full factorial 2k experimental design. Kinetic and thermodynamic studies were also carried out. The adsorption kinetics was found follow a pseudo-second-order model. The adsorption data fit better to the Langmuir isotherm. The ANOVA demonstrated that both pH of the solution and activated carbon dosage had the greatest influence on copper adsorption. The activation energy was -32 kJ·mol-1 suggesting that the copper adsorption is a physic-sorption process. The best fit to a linear correlation was the moving boundary equation that controls the kinetics for the adsorption copper ions onto the activated carbon. The X-ray photoelectron spectroscopy (XPS) results reveal the existence of different copper species (Cu2+, Cu+ and or Cu0) on the surface of the carbonaceous adsorbent after the adsorption, which could suggest a simultaneous reduction process.

Phase configuration, nanostructure, and mechanical behaviors in Ti-B-C-N thin films

2009 ◽  
Vol 24 (8) ◽  
pp. 2520-2527 ◽  
Author(s):  
Yonghao Lu ◽  
Junping Wang ◽  
Yaogen Shen ◽  
Dongbai Sun
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Solid Solution Hardening ◽  
Mechanical Behaviors ◽  
Additional Increase ◽  
N Content ◽  
X Ray ◽  
Nanocomposite Thin Films ◽  
The Cost ◽  
Nano Grains

A series of Ti-B-C-N thin films were deposited on Si (100) at 500 °C by incorporation of different amounts of N into Ti-B-C using reactive unbalanced dc magnetron sputtering in an Ar-N2 gas mixture. The effect of N content on phase configuration, nanostructure evolution, and mechanical behaviors was studied by x-ray diffraction, x-ray photoelectron spectroscopy, Raman spectroscopy, high-resolution transmission electron microscopy, and microindentation. It was found that the pure Ti-B-C was two-phased quasi-amorphous thin films comprising TiCx and TiB2. Incorporation of a small amount of N not only dissolved into TiCx but also promoted growth of TiCx nano-grains. As a result, nanocomposite thin films of nanocrystalline (nc-) TiCx(Ny) (x + y < 1) embedded into amorphous (a-) TiB2 were observed until nitrogen fully filled all carbon vacancy lattice (at that time x + y = 1). Additional increase of N content promoted formation of a-BN at the cost of TiB2, which produced nanocomposite thin films of nc-Ti(Cx,N1-x) embedded into a-(TiB2, BN). Formation of BN also decreased nanocrystalline size. Both microhardness and elastic modulus values were increased with an increase of N content and got their maximums at nanocomposite thin films consisting of nc-Ti(Cx,N1-x) and a-TiB2. Both values were decreased after formation of BN. Residual compressive stress value was successively decreased with an increase of N content. Enhancement of hardness was attributed to formation of nanocomposite structure and solid solution hardening.

scholarly journals Optical Constant and Conformality Analysis of SiO2 Thin Films Deposited on Linear Array Microstructure Substrate by PECVD

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 510
Author(s):  
Yongqiang Pan ◽  
Huan Liu ◽  
Zhuoman Wang ◽  
Jinmei Jia ◽  
Jijie Zhao
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Deposition Rate ◽  
Optical Constant ◽  
Photoelectron Spectroscopy ◽  
Linear Array ◽  
Chemical Vapor ◽  
Rf Plasma ◽  
X Ray ◽  
Sio2 Thin Film

SiO2 thin films are deposited by radio frequency (RF) plasma-enhanced chemical vapor deposition (PECVD) technique using SiH4 and N2O as precursor gases. The stoichiometry of SiO2 thin films is determined by the X-ray photoelectron spectroscopy (XPS), and the optical constant n and k are obtained by using variable angle spectroscopic ellipsometer (VASE) in the spectral range 380–1600 nm. The refractive index and extinction coefficient of the deposited SiO2 thin films at 500 nm are 1.464 and 0.0069, respectively. The deposition rate of SiO2 thin films is controlled by changing the reaction pressure. The effects of deposition rate, film thickness, and microstructure size on the conformality of SiO2 thin films are studied. The conformality of SiO2 thin films increases from 0.68 to 0.91, with the increase of deposition rate of the SiO2 thin film from 20.84 to 41.92 nm/min. The conformality of SiO2 thin films decreases with the increase of film thickness, and the higher the step height, the smaller the conformality of SiO2 thin films.

scholarly journals A novel and potentially scalable CVD-based route towards SnO2:Mo thin films as transparent conducting oxides

2021 ◽  
Author(s):  
Tianlei Ma ◽  
Marek Nikiel ◽  
Andrew G. Thomas ◽  
Mohamed Missous ◽  
David J. Lewis
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Mixed Valence ◽  
Chemical Vapour ◽  
X Ray Diffraction ◽  
X Ray ◽  
Conducting Oxides ◽  
Valence States ◽  
3 Omega ◽  
First Time

AbstractIn this report, we prepared transparent and conducting undoped and molybdenum-doped tin oxide (Mo–SnO2) thin films by aerosol-assisted chemical vapour deposition (AACVD). The relationship between the precursor concentration in the feed and in the resulting films was studied by energy-dispersive X-ray spectroscopy, suggesting that the efficiency of doping is quantitative and that this method could potentially impart exquisite control over dopant levels. All SnO2 films were in tetragonal structure as confirmed by powder X-ray diffraction measurements. X-ray photoelectron spectroscopy characterisation indicated for the first time that Mo ions were in mixed valence states of Mo(VI) and Mo(V) on the surface. Incorporation of Mo6+ resulted in the lowest resistivity of $$7.3 \times 10^{{ - 3}} \Omega \,{\text{cm}}$$ 7.3 × 10 - 3 Ω cm , compared to pure SnO2 films with resistivities of $$4.3\left( 0 \right) \times 10^{{ - 2}} \Omega \,{\text{cm}}$$ 4.3 0 × 10 - 2 Ω cm . Meanwhile, a high transmittance of 83% in the visible light range was also acquired. This work presents a comprehensive investigation into impact of Mo doping on SnO2 films synthesised by AACVD for the first time and establishes the potential for scalable deposition of SnO2:Mo thin films in TCO manufacturing. Graphical abstract

scholarly journals X-ray Photoelectron Spectroscopy Analysis of Chitosan–Graphene Oxide-Based Composite Thin Films for Potential Optical Sensing Applications

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 478
Author(s):  
Wan Mohd Ebtisyam Mustaqim Mohd Daniyal ◽  
Yap Wing Fen ◽  
Silvan Saleviter ◽  
Narong Chanlek ◽  
Hideki Nakajima ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Functional Group ◽  
Optical Sensing ◽  
Composite Thin Films ◽  
Cobalt Ions ◽  
X Ray ◽  
Sensing Applications

In this study, X-ray photoelectron spectroscopy (XPS) was used to study chitosan–graphene oxide (chitosan–GO) incorporated with 4-(2-pyridylazo)resorcinol (PAR) and cadmium sulfide quantum dot (CdS QD) composite thin films for the potential optical sensing of cobalt ions (Co2+). From the XPS results, it was confirmed that carbon, oxygen, and nitrogen elements existed on the PAR–chitosan–GO thin film, while for CdS QD–chitosan–GO, the existence of carbon, oxygen, cadmium, nitrogen, and sulfur were confirmed. Further deconvolution of each element using the Gaussian–Lorentzian curve fitting program revealed the sub-peak component of each element and hence the corresponding functional group was identified. Next, investigation using surface plasmon resonance (SPR) optical sensor proved that both chitosan–GO-based thin films were able to detect Co2+ as low as 0.01 ppm for both composite thin films, while the PAR had the higher binding affinity. The interaction of the Co2+ with the thin films was characterized again using XPS to confirm the functional group involved during the reaction. The XPS results proved that primary amino in the PAR–chitosan–GO thin film contributed more important role for the reaction with Co2+, as in agreement with the SPR results.

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